Acetoacetic acid esters of castor oil and the use thereof in plasticization



United States Patent ACETOACETIC ACID ESTERS F CASTOR OIL AND THE USETHEREOF IN PLASTICIZATION Alfred R. Bader, Milwaukee, Wis, and Henry A.Vogel,

Gibsonia, Pa., assignors to Pittsburgh Plate Glass Company No Drawing.Application November 12, 1954 Serial No. 468,556

3 Claims. (Cl. 106-195) This invention relates to beta-keto esters ofcastor oil and to the use thereof in the plasticization of resins and ithas particular relation to the use of said beta-keto esters in theplasticization of nitrocellulose and other plastic materials.

It has heretofore been recognized that valuable plastic could be formedby incorporation of plasticizing agents, such as so-called oilplasticizers, namely castor oil; or chemical plasticizers, such asesters of phthalic acid, into nitrocellulose and other plasticmaterials. The resultant materials were valuable resins in the moldingarts and for forming films, such as photographic films. They were alsodissolved in appropriate solvents, such as acetone; esters, such as amylacetate, or ethyl acetate; hydroxy ethers, such as monoethers ofethylene glycol, or diethylene glycol, or the like, with or withoutpigments to provide solutions which could be applied as lacquers tosurfaces of various materials, such as wood, metal or the like, anddried by evaporation of solvents to form adherent protective and/ ordecorative films. Such systems have been extensively used in the coatingand molding arts. However, they were not always entirely satisfactory.For example, it has been recognized that the oil plasticizers, such ascastor oil, exhibited a pronounced tendency to sweat out or migrateduring aging, especially if exposed to elevated temperatures. Chemicalplasticizers, such as the phthalic acid esters, e.g., diethyl phthalateor dibutyl phthalate, were not entirely satisfactory, inasmuch as theesters tended to be volatile and during the course of the aging of thefilms, the plasticizers gradually evaporated, leaving the filmsunplasticized and of course highly embrittled.

It has now been discovered that the acetoacetic acid esters ofhydroxylated fatty acids and glycerol and more particularly theacetoacetic acid esters of castor oil are highly meritoriousplasticizers of plastic and particularly of nitrocelulose. Theseplasticizers are in many respects superior to such standard materials ascastor oil and the esters of phthalic acid, since they do not sweat outor migrate, at least to a substantial degree and they are relativelynon-volatile.

Castor oil, as is well known, contains free hydroxyls, since it consistslargely of triglycerides of ricinoleic acid(l2-hydroxy-9,IO-octadecenoic acid). Esters of acetoacetic acid andcastor oil may be prepared by various methods. However, the methoddisclosed in Patent 2,- 693,484 issued to applicants and another as ofNovember 2, 1954, is satisfactory. This method broadly involves mixingcastor oil with a lower ester (e.g., methyl or ethyl ester) ofacetoacetic acid and heating the mixture at ester interchangetemperatures (e.g., 75 C. to 125 C.). Acetoacetic acid esters of castoroil are formed by exchange of castor oil radicals for alkyl groups ofthe acetoacetic acid ester, and lower alcohol is evolved, preferablybeing removed as it is formed. The ester interchange reaction involvesthe hydroxyl group of the ricinoleic acid radicals.

Still another simple method of forming acetoacetic acid esters of castoroil comprises reacting castor oil in approximately stoichiometric amountwith diketene. This reaction proceeds at room temperature and maybe ac-Patented July 21, 1959 celerated by heating or by the addition of asmall amount of a mild catalyst.

This latter reaction is illustrated as follows:

Mix 31 grams of pure castor oil with 8.4 grams diketene and 0.2 grampyridene (catalyst) dissolved in milliliters of toluene. Heat themixture on a steam bath over night and strip under vacuum to removevolatile components. The yield is 39 grams of faintly yellow,substantially pure castor oil acetoacetate suitable for use as aplasticizer for nitrocellulose, in accordance with the provisions ofthis invention.

When plasticizing nitrocellulose the acetoacetic acid esters may beemployed in a range of about 5 to 200 parts per part of nitrocellulose.The plasticization of nitrocellulose with acetoacetic acid esters ofcastor oil may be effected by various techniques well understood in theart. For example, the tWo materials may be milled together in a pebblemill or other suitable device. However, it is more common to incorporatethe plasticizer' into a solu tion of nitrocellulose and an appropriatesolvent system therefor. Solvent systems for nitrocellulose includeactive solvents with or without addition of latent solvents and with orwithout additions of diluents.

Active solvents of nitrocellulose which may be employed in thepreparation of solutions for plasticization, in accordance with theprovisions of the present invention, include a relatively large class ofliquid media such as: Ketones such as,

Methyl ethyl ketone Acetone Esters such as,

Methyl acetate Isopropyl acetate Isobutyl acetate Butyl acetate Amylacetate Secondary amyl acetate Butyl propionate Monoethers of ethyleneglycol such as,

Monomethyl ether of ethylene glycol Monoethyl ether of ethylene glycolMonobutyl ether of ethylene glycol. Numerous other solvents areavailable.

Well recognized latent solvents which may be employed in combinationwith the foregoing active solvents comprise: I

Ethyl alcohol Isopropyl alcohol Isobutyl alcohol Butyl alcohol Amylalcohol Diluents which may be added to the solutions for purposes ofextending them comprise the well known hydrocarbons such as:

Benzol Toluol Xylol Aromatic solvent naphtha Aliphatic petroleumfractions Hydrogenated petroleum fractions Selection of solvents anddiluents for the nitrocellulose compositions of this inventionpreferably is made in accordance with the volatility or speed of dryingrequired in the films after application. In those instances where rapiddrying is a prerequisite, highly volatile solvents are employed. On theother hand, in those instances where a slow rate of drying is desirable,less volatile solvents should be employed. Amounts of solvent employedwill vary, dependent upon the mode of application of the film,temperatures at which the solutions are applied and other factors.

It should be recognized that nitrocellulose lacquers are often modifiedby incorporation of various resinous materials, such as gum dammar,ester gum, alkyd resins, urea resins, ethyl cellulose and the like.These same 4 mixture to which acetoacetic acid esters of castor oil wereadded and several sets of samples were prepared from the mixture. Thesewere distinguished from each other by variation of the proportion of theplasticizers modifying materials may be successfully incorporated 5employed. These sets were as follows: with nitrocellulose which isplasticized by means of Set 1 acetoacetic acid esters of castor oil. D

It is likewise common to incorporate mixtures of vari- I11 thls Set thhplashcllel's P Y 111 a who ous of the recognized plasticizers in place'of single plasof 79 Pounds P 100 Pounds 0f hltfocelluloseticizers. Forexample, chemical plasticizers including dis 2 butyl phthalate,di-n-octyl phthalate, di-Z-ethylhexyl phthalate, diamyl phthalate,tricresyl phosphate, triphenyl In th ls Set of Samples the p tlclzerswere employed phosphate, tributyl phosphate, triacefin, butyl steam/w,in a ratio of 112 pounds per 100 pounds of mtrocellulose. butyltartrate, triethylene citrate; or oil plasticizers, such S 3. as rawcastor oil, linseed oil, tung oil, blown soya oil, 15 blown rapeseedoil, blown wood oil and blown castor oil, 1 sggs g fi gfifig g g f i g igg a who of be e o d 'n variou ombinations of two or more fig gg g s;efiects These same p1 All of the foregoing samples were well plasticizedand ticizers and mixtures thereof may also be employed if were caPableof formmg useful films Wood metal desired in combination with theacetoacetic acid esters zgigfgggxgg x Useful moldmgs could also ofplasticizers may be employed in amounts for example with castor 011 anddibutyl phthalate in amounts of 79 of 5 percent to 75 percent of thetotal weight of the plas pounds i 100 Pounds of mtmceuulose Thefollowing ticizer mixture comparative tests were conducted upon thesesamples and It is to be recognized that nitrocellulose solutions are i gZg $f g g fi materials by means t'mes lo ed as clear films but the arealso uite 2:1: admii e cl v ith coloring agents suZh as the well of.anapprognate apphcatfn" the thlckness of the films known pigments such astitanium dioxide carbon black P .approxlmately 0003 The msultant films il lithopone or like in order to impart opacity or air dried and werethen examined for such characteristic desired color to the films.Nitrocellulose material conpropeltles as clanty sweat'out hardness and(501m taining acetoacetic acid esters of castor oil may also be f g 2 1ig 3' i g gg g z g f zg gi g fig employed as clear solutions or they maybe pigmented in swad hardnesg valugs and flexibifit g ry the mannercharacterizing nitrocellulose materials. To Th i th d t t ts obtainpigmentation, the pigmentary material and a solu- 35 of i f 23: d 16c 0exposure es tion of the plasticized nitrocellulose are mixed together jg i gg were baked for 1 hour inmalii-ikeappropnate apparatus, such as apebble mill or at F. and were then waxamined.

Nitrocellulose plasticized with acetoacetic acid esters 1 In the palkedl It was ffmnd that. m mtroceuu of castor oil may be applied to wood, ormetals, such 40 056 Plasnclzed wlth castor a conslderabei l O as iron orsteel by the conventional methods. Such Sweatmg out had The filmscoinammg butyl methods comprise dipping brushing, roller coating, orphthalate as a plastlcizer had to a substantial degree lost spraycoating. Naturally it will be recognized that for the latter thloughevaporatlon and the films liemlnnmg these various methods ofapplication, the solutions should z gg g i' acfitoaietafte of g i fi beproperly thinned with solvents and/or diluents to ata w c tain therequisite degree of viscosity adapted for the parwlt T 6 ms contammg.were ticular method of application to be employed st1ll well plasticlzedand of good color after baking.

The use of the acetoacetic acid ester of castor oil as Fllms of theforegomg mjatenals were sprayed onto a plasticizer for nitrocelluloseand the comparison thereof Panels and then stPPPed F for test Purposes'with such standard plasticizers as castor oil and dibutyl The filmsekposfa'd 75 for 64 at phthalate are illustrated by the followingexamples: the concluslon of which time, it was found substantially allof the dibutyl phthalate had evaporated from those EXAMPLE I films whichwere plasticized with it. Further films were In order to form an esterof castor oil and acetoacetic tested for elongation and tensileStrength; as initially acid, 800 grams of castor oil and 200 grams ofmethyl formed and dfled; after eXpOsufe at C r 64 acetoacetate weremixed in a flask provided with an air hours and after exposure to atemperature of condenser. The mixture was heated for six hours at for 1hour The toughness factor Was Calcu- C. while being blown gently withinert gas to remove lated from the formulae! evolved methyl alcohol.Vapors of methyl acetoacetate ES were condensed and returned during thereaction. At the 0 7 end of the reaction, the mixture was blownvigorously to remove any volatile matter. The acetoacetic acid esterswhere E equals the percent extension of the sample be of castor oil wereproduced in almost theoretical yield. fore break and S equals thetensile strength in pounds Nitrocellulose was dissolved in a blend ofethyl acetate, per square inch. The results of these tests are asfolethyl alcohol, and methyl ethyl ketone to provide a fluid 55 lows:

Initial 64 hours at 75 C. 1 hour at 275 F.

Plastielzer Percent Tensile Tough- Percent Tensile Tough- PercentTensile Tough- Elonga- S ness T Elonga- S ness T Elonga- S ness T tlon Etion E tion E glilif llrttatta 35'? 933 1? 333 1 31695 33 i 9'Acetoaeetlc ester of'eii'filQI 013 1,805 51680 12.2 2, 420 14,800 8.3.9005 700 1 T00 brittle to test.

From these tests, it will be observed that although dibutyl phthalateplasticized materials were initially of high elongation and hightoughness factor, these properties were quickly lost when the films wereheated in the accelerated aging test. As previously intimated, thosematerials plasticized with castor oil tended to lose the latter bymigration. However, the elongation, tensile strength and generaltoughness of the films was better than in the case of those materialsplasticized with dibutyl phthalate. On the other hand, in the materialplasticized with the acetoacetic acid esters of castor oil theelongation, tensile strength and toughness in every instance wassuperior to that of the films as initially laid down. The acetoaceticacid esters of castor oil did not sweat out.

EXAMPLE II In accordance with this example, 50 grams of cold pressedcastor oil and 150 grams of methyl acetoacetate were heated in anopen-necked glass flask on a steambath for 4 hours. The mixture at thatpoint was a clear solution which was stripped of methyl acetoacetate andresidual methyl alcohol by distillation at millimeters mercury pressure(absolute) to leave a light yellow oil of a weight of 62 grams. Thisproduct is castor oil acetoacetate in which infrared analyses showed thecomplete absence of hydroxyl groups. A mixed lacquer formulation wasprepared comprising:

50 grams of a 35 percent solution of nitrocellulose (12 sec. viscosity)in a mixture of butyl acetate, ethanol, isopropyl acetate, and toluene10 grams butyl acetate 10 grams castor oil acetoaeetate (prepared asabove described) The resultant solution was clear. A film thereof bakedon glass for 1% hours at 100 C. was hard but not brittle. Thecomposition contained 10 grams of plasticizer and 17.5 grams ofnitrocellulose.

The material could also successfully be applied as a coating film towood, iron, steel or the like materials for decorative and/ orprotective purposes.

EXAMPLE HI In accordance with this example, castor oil acetoacetateprepared as above described is employed as a plasticizer for a vinylresin, namely, so-called VMCH, which is understood to be a copolymer of86 parts of vinyl chloride, 13 parts of vinyl acetate, and 1 percentmaleic acid. The vinyl resin was employed as a solution of 25 percentsolids content in a mixture of methyl isobutyl ketone, methyl ethylketone, and toluene. To 50 grams of the purposes. 7 p v p EXAMPLE IV Inaccordance with this example, nitrocellulose as in Example I wasemployed. It was mixed with acetoacetic acid esters and saturated alkydresin, respectively in the proportions of 62 pounds and 56 pounds perpounds of the nitrocellulose employed. This plasticized material wasmade up as a clear solution and applied to glass panels for testingpurposes. The films were found to be well plasticized and the materialwas apparently suitable for use in coating wood and metals. This mixtureillustrates the application of the esters of acetoacetic acid and castoroil to the plasticization of mixtures of nitrocellulose and alkydresins. It will be apparent that other modifiers of nitrocellulose, suchas ester gum, gum dammar and many other resinous materials, might besubstituted for the alkyd resin of this example to provide compositionssuitable for various applications.

It will be apparent to those skilled in the art that the embodiments ofthe invention as herein given are by way of illustration and not oflimitation. Manifestly various modifications may be made therein, bothfrom the standpoint of proportions of the several components and ofsubstitution of materials, without departure from the spirit of theinvention or the scope of the appended claims.

We claim:

1. Nitrocellulose plasticized with the acetoacetic acid ester of castoroil.

2. A solution of nitrocellulose and as a plasticizer therefor, theacetoacetic acid ester of castor oil.

3. A solution of a mixture of nitrocellulose and the acetoacetic acidester of castor oil in a solvent for nitrocellulose.

The Condensed Chemical Dictionary, fourth edition (1950), Rheinhold.

Fleck: Plastics-Scientific and Technological, Chemical gublishing Co.,Inc. (second, revised edition), 1949, page

1. NITROCELLULOSE PLASTICIZED WITH THE ACETOACTIC ACID ESTER OF CASTOROIL.